Gut-related peptides include ghrelin secreted by the stomach and the duodenum has orexigenic (appetite stimulating) effect; leptin secreted by adipose tissue has anorexic (appetite inhibiting) effect, cholecystokinin, glucagon-like peptide-1 (GLP-1) secreted by the proximal gastrointestinal tract which has slight anorexic effect, and peptide YY (PYY).